Spark plug



June 22, 1943.

T. L. CARSON EFAL SPARK PLUG Filed April 13, 1942 INVENTORS:

Theodore L. Caruso/z (7353/ J? .Z-Ywoww Patented June 22, 1943 SPARK PLUG Theodore L. Carson and Jay F. Brown, Denver,

Colo., assignors Waukesha, Wis.,

to Waukesha Motor Company,

a corporation of Wisconsin Application April 13, 1942, Serial No. 438,750

' 3 Claims.

This invention relates to spark plugs for use in internal combustion engines.

Our invention is directed to the provision of a spark plug in which the electrodes have long life, are rigidly supported so as to avoid distortion and be maintained in proper spaced apart relation, and are so disposed as to assure quick ignition of the fuel mixture charge within the combustion chamber of the engine. More specifically, the electrodes are of considerable area and mass, to avoid objectionable burning and corrosion thereof, are maintained at proper temperature to assure vaporizing of fuel coming in contact therewith, are disposed to confine between them a stratum o-f vaporized fuel efiective for assuring rapid ignition of the fuel mixture, and the ground electrode is supported by a heat conducting element of considerable extent effective for preventing overheating of that electrode. Further objects and advantages of our invention will appear from the detail description.

In the drawing:

Figure 1 is a side view, shown partly-broken away and in section, of a spark plug embodying our invention, on an enlarged scale;

Figure 2 is a view of the lower portion of the plug, as seen from the cut-away side of the neck thereof, the lower end of the neck being partly broken away and shown in section;

Figure 3 is a sectional view tak n substantially on line 33 of Figure 2; T

Figure 4 is a view similar to Figure 2 of a modified form of plug embodying our invention; and

Figure 5 is a sectional view taken substantially on line 5-5 of Figure 4.

The spark plug of our invention is, in general, of known construction, and a brief description thereof, except as to the features which we consider novel, will suffice. It comprises a shell or body 6 formed of metal, within which is mounted a porcelain core 1 secured tightly in position by a gland nut 8 screwing into the upper end of the body 6 andbearing, at its lower end, on a cup-shaped gasket 9, conveniently formed of copper, within which is disposed a ring I0, also formed of copper, seating upon the upper face of a shoulder H of core 1. Body 6 is provided with an interior shoulder |2 upon which seats a gasket l3, preferably formed of copper, confined between shoulder l2 and a lower shoulder ll of core 1. Body 6 is open at its lower end and core 1 extends downwardly therethrough and therebeyond, as shown, this core being secured tightly in position within body 6, in concentric relation thereto, by means of nut 8 and the cooperating gaskets and shoulders so as to provide a fluid-tight and pressure resistant closure about the core, as will be understood. An electrode rod l5 of cylindrical shape is mounted through core 1 and extends above and below the latter, there being a metal cap l6 secured upon the upper end of core I and provision being made for connecting the upper end of rod l5 to a wire or conductor, as is known.

Rod I5 is of considerable thickness and provides a rigid support for a cylindrical discshaped head i! secured upon the lower end of this rod. Head I1 is formed of a heat and corrosion resisting alloy and is suitably secured, conveniently by welding, to rod IS, with an intervening element l8 which flares downward and outward to the periphery of head ll in a smooth curve, as shown. If desired, the rod I5 and head l1, including the element |8, may be formed initially as a unit and from an alloy having the desired heat and corrosion resisting qualities, though ordinarily we preferably form the head I! as a separate element and then unite it with a rod by welding.

Body 6 is provided with a depending neck 20, the upper portion 20a of which is threaded for securing the spark plug in the cylinder head of an engine, in the usual manner. Neck 20 is provided at its lower end with a firing plate 2| of greater extent than the lower face of firing head I! and spaced a short distance therebelow, defining therewith a spark gap 22. Preferably, plate 2| is in the form of a disc of considerable thickness, this disc being of uniform thickness and provided with a circular opening 23 disposed coaxially and concentrically with head Neck 20 has its lower portion cut away from one side for substantially one-half of its circumference. at 24, and is otherwise closed except for the opening 23. The firing plate 2| is formed of a heat and corrosion resisting allow, and preferably is initially made as a unit separate from neck 20, to which plate 2| is integrally united by welding. If desired, both the plate 2| and neck 20 may be formed as a unit from an alloy having the desired qualities, neck 20 being welded to body 6, or, if desired, body 6 and neck 20 and the plate 2| may all be formed from an alloy having the desired heat and corrosion resisting characteristics. Preferably, however, firing plate 2| is formed of an alloy having the desired qualities with respect to heat and corrosion resistance, and is welded to neck 20, the

latter and body 6 being formed of steel or other suitable metal which is a good heat conductor.

In the use of the spark plug above described. the plug is secured in the cylinder head of the engine with theopening 24 properly disposed relative'to the combustion chamber. The firing head I! and the firing plate 2| are quickly heated to a temperature such that fuel coming in contact therewith is readily vaporized, spark gap 22 serving to retain between the opposed faces of head I1 and plate 2i a thin layer or stratum of vaporized fuel. When a spark passes between head I! and plate 2| this stratum of fuel vapor is ignited, causing an initial localized explosion within the gap 22, the flame resulting from this explosion being projected radially outward from gap 22 into the combustion chamber of the engine and serving thus quickly to ignite the fuel mixture charge within the chamber. The head IT and plate 2i present surfaces of considerable area effective for preventing or reducing corrosion or burning of the electrodes of the spark plug. Further, head I1 and plate 2i each possess considerable mass and are readily maintained at vaporizing temperatures, the neck 20 and body 8 providing a path for ready flow of heat from firing plate 2! to the cylinder head and the coolant circulated therethrough, thus preventing overheating of plate 2| and also of head H, the latter radiating its excess heat to plate 2i and neck 20. By properly proportioning the parts, head I? and plate 2i may be maintained at the proper temperature to assure vaporizing of the fuel in the manner described, and overheating of these elements may be guarded against. The neck 20 and plate 2! together provide a shroud substantially surroundmg the lower portion of rod i and the head II, in a manner to shield them from excessive heating by the combustion occurring within the engine. That, in conjunction with the comparatively large areas and mass of the head l1 and the plate 2!, formed from corrosion and heat resistant alloys, prevents or greatly reduces burning and corrosion of the electrodes, assuring long life thereof. Flow of gases through opening 23 and gap 22, during operation of the engine, effectively prevents accumulation of unvaporized fuel within this gap, while also preventing formation of carbon therein. That, in conjunction with the avoidance of pointed projections or elements of like character, guards against fouling of the electrodes while also being conducive to long life thereof.

The spark plug of the modified form shown in Figures 4 and 5 is similar to that shown in Figures 1 to 3, inclusive, with the exception that opening 23a in firing plate Zia is of slightly greater diameter than head I1, the latter being disposed within opening 23a in concentric spaced relation thereto, defining with the surrounding which such elements are subjected, thus assuring that the firing head and the firing plate are maintained in proper spaced apart relation. In the plug of Figures 4 and 5, the fuel is vaporized by contact with plate 2m and head I1, and an annular layer or stratum of fuel vapor is confined within the spark gap 22a, this layer being ignited upon passage of a spark and the ensuing localized explosion serving to cause rapid ignition of the fuel mixture charge within the combustion chamber. Flow of gases through the spark gap 22a, in the operation of the engine.

' efiectively prevents collection of unvaporized wall thereof an annular spark gap 22a. The" fuel or of carbon within the spark gap, which, in conjunction with the avoidance of pointed elements or fiat shoulders, or equivalent elements, prevents fouling of the electrodes of the plug and assures long life thereof.

We claim:

1. In a spark plug, a metal body and an insulating core mounted therein, an electrode rod extending through said core provided at its lower end with a relatively large disc-shaped head, and a neck integral with said body depending therefrom in substantially concentric paced relation to said head provided with a fiat disc-shaped firing plate of uniform thickness defining with said head a spark gap, said plate having an opening therethrough concentric with said head, said neck having its lower portion cut away from one side for substantially one half of its circumference and being otherwise closed except for the opening in said plate.

2. In a spark plug a metal body and an insulating core mounted therein, a cylindrical electrode rod extending through said core provided at its lower end with a disc-shaped head of materially greater diameter than said rod with an intervening portion flaring outward above and merging into said head at the periphery thereof, and a neck integral with said body depending therefrom in substantially concentric spaced relation to said head provided at its lower end with a flat disc-shaped firing plate defining with said head a spark gap, said plate having an opening therethrough concentric with said head, said neck having its lower portion cut away from one side for substantially one half of its circumference and being otherwise closed except for the opening in said plate.

3. In a spark plug, a metal body and an insulating core mounted therein, an electrode rod extending through said core provided at its lower end with a disc-shaped head having a lower face of considerable area, and a neck integral with said body depending therefrom in substantially concentric spaced relation to said head provided at its lower end with a fiat discshaped firing plate of uniform thickness below said head defining therewith a spark gap, said plate having an opening therethrough concentric with and of materially less diameter than said head, said neck having its lower portion cut away from one side for substantially one half of its circumference and being otherwise closed except for the opening in said plate.

THEODORE L. CARSON. JAY F. BROWN. 

